APIs to Delete leaf Configuration from GC
One answer
The APIs provided by GCM are documented on your server https://SERVER:PORT/gc/doc/scenario - there's one called "Update a global configuration" - you'll GET the gc details, modify the content of (presumably) the oslc_config:contributions, then PUT which uses that API to update the GC. The doc shows content in text/turtle but this API also works in application/rdf+xml and text/json.
NOTE this will only change what's in GC it won't affect the applications which provide contributions.